Anatomical variations of the pulmonary hilum in Nepalese population: a contrast CT scan study

Abstract

Introduction: The pulmonary hilum is where bronchi, pulmonary vessels, and lymphatics converge; variations in its arrangement can influence thoracic surgical planning, bronchoscopy, and radiological interpretation. Existing evidence derives largely from cadaveric studies, and in vivo, population-specific South Asian data remain limited. This study aimed to determine the prevalence and pattern of pulmonary hilar variations in a Nepalese population using contrast-enhanced chest CT.

Method: This descriptive cross-sectional study was conducted from January 2025 to January 2026 at the Department of Radiology and Imaging, Patan Academy of Health Sciences, Patan Hospital, Nepal, with ethical approval from the Institutional Review Committee (Ref no: drs2501171982). Using stratified random sampling, 369 participants were recruited, with sample size calculated from prior prevalence data. Adults aged 16 years and above undergoing contrast-enhanced chest CT for diagnostic purposes were included; those with prior thoracic surgery, pregnancy, or CT contraindications were excluded. CT images were reviewed by radiologists to classify hilar arrangements, and analysed descriptively using R.

Result: Of 369 participants, 219 (59.35%) were female and 150 (40.65%) male, mean age 56.81±15.82 years (range 16-93). On the right, Type B (36.04%) and Type E (22.76%) were most common; on the left, Type A (34.69%) and Type E (30.62%) predominated. Bilateral symmetry was seen in 86 (23.31%), most often as E-E (8.40%) and A-A (7.59%).

Conclusion: Contrast-enhanced CT revealed diverse, clinically relevant hilar variations in this Nepalese cohort, with Type B most common on the right and Type A on the left, supporting population-specific anatomical mapping for surgical planning.